Increasing the dose of the antimuscarinic drug solifenacin can improve outcomes in patients with more severe overactive bladder (OAB) symptoms, data show.

In a 16-week trial, Linda Cardozo, MD, of King’s College Hospital in London, and collaborators examined the efficacy of 5 and 10 mg solifenacin doses in relieving OAB symptoms in patients who requested a dose increase. The investigators randomized patients to double-blind treatment with solifenacin or placebo once daily. At week 8, all patients could request a dose increase. These patients entered a second phase of eight weeks in which those in the solifenacin group were randomized to either 5 or 10 mg doses.

Of 591 patients receiving solifenacin at eight weeks, 275 (46.5%) requested a dose increase to 10 mg, according to findings published online ahead of print in BJU International. Investigators randomized 140 patients to receive 10 mg doses and 135 to remain on 5 mg doses. The primary efficacy variable was the mean change in the number of urgency episodes with or without incontinence per 24 hours measured using the Patient Perception of Intensity of Urgency Scale (PPIUS).

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Compared with patients who did not request a dose increase, those who did request an increase at week 8 generally had more severe OAB symptoms at baseline and a smaller response at week 8 to the initial 5 mg dose.

Patients requesting a dose increase and who were randomized to 10 mg doses of solifenacin had greater reductions in the mean number of severe urgency episodes from week 8 to the end of treatment compared with those randomized to remain on 5 mg doses, but these reductions were not statistically significant, according to the researchers. The investigators, however, observed statistically significant reductions in mean total urgency score, mean maximum PPIUS urgency rating, and mean micturition frequency.

“The present study supports the view that patients with severe OAB symptoms benefit from a higher antimuscarinic dose,” the authors concluded.